1. Field of the Invention
The present invention relates to a plasma processing apparatus using surface wave plasma.
2. Description of the Related Art
Plasma technology has been heretofore often used in semiconductor manufacturing processes for coating, etching, ashing and so on. In addition, plasma technology has been also used for manufacturing solar cells, liquid crystal displays, plasma displays, etc. Recently, with increase in panel size or screen size, large-area plasma processing techniques have come to be essential. To that end, it is necessary to generate large-area and high-density plasma uniformly. If the plasma density is uniform, uniform plasma processing can be performed all over a surface of a substrate.
As a plasma processing apparatus capable of generating large-area and high-density plasma, an apparatus using surface wave plasma (SWP) is known (e.g., see Japanese Patent Laid-Open No. 2000-348898 (page 2, FIG. 1)). In this apparatus, microwaves being transmitted in a waveguide are introduced into a plasma generating chamber from a slot antenna through a dielectric window so that process gas in the plasma generating chamber is excited by surface waves generated at a surface of the dielectric window facing the plasma generating chamber. The surface waves are transmitted promptly on the plasma generating in chamber of the dielectric window so that a plasma area corresponding to the surface area of the dielectric window can be obtained easily. The dielectric window is manufactured out of a dielectric material.
In the related-art apparatus, it cannot be said that the surface wave energy is transmitted all over the surface of the dielectric window uniformly. Thus, the related-art apparatus is not satisfactory in terms of equalization of the plasma density distribution. This is caused by the fact that the shape of an aperture, layout or the like, of the slot antenna does not always conform to the electromagnetic filed distribution generated inside the microwave waveguide.